build: Set ccache base to build top

This enables ccache sharing between different build tree paths.

Change-Id: I99636bdd2779a6ccf0649f027e35cf67df44b6ae
Signed-off-by: Chet Kener <Cl3Kener@gmail.com>
Don't set CCACHE_BASEDIR if its already set

 * enable use of shared ccache

Change-Id: Ic708a5d5169291d674b167aa2c87bf2c8adaafae
Signed-off-by: Chet Kener <Cl3Kener@gmail.com>
Apply correct, optimized mfpu compiler flag for ARMv7-A Cortex CPUs

For those ARMv7-A Cortex CPUs that can handle VFPv4 floating point,
We can set "-mfpu=neon-vfpv4" instead of generic "-mfpu=neon"
to gain extra performance improvements.

References :
 - GCC		: https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html
 - Cortex A15	: http://www.arm.com/products/processors/cortex-a/cortex-a15.php
 - Cortex A9	: http://www.arm.com/products/processors/cortex-a/cortex-a9.php
 - Cortex A8	: http://www.arm.com/products/processors/cortex-a/cortex-a8.php
 - Cortex A7	: http://www.arm.com/products/processors/cortex-a/cortex-a7.php
 - Cortex A5	: http://www.arm.com/products/processors/cortex-a/cortex-a5.php

Change-Id: Id8b1a251234014ecf7ffbc1ae14455ed1726e028
Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>
Signed-off-by: Chet Kener <Cl3Kener@gmail.com>

Conflicts:
	core/combo/arch/arm/armv7-a-neon.mk